The present invention relates in general to data communication, and more specifically to a system and method of operation for managing data communication between physical layer devices and ATM layer devices.
Asynchronous transfer mode (ATM) communication systems are widely used for network communications. In general, ATM communication protocols involve stacks having several layers including a physical layer as the lowest layer. The ATM physical layer typically involves the movement of cells between source and target physical layer devices. The cells are often moved across a bus in smaller parallel sets of data. When the data reaches the target device, the cell is reconstructed and then sent up the stack to its final destination. One example of an ATM physical layer protocol is the UTOPIA 2 protocol. The physical layer devices, between which data must be moved at the ATM physical layer, can, and often do, have varying data rates.
In accordance with the present invention, a system and method of operation for managing data communication between physical layer devices are disclosed. This system and method provide advantages over those previously developed systems.
According to one aspect of the present invention, a system is provided for managing data communication between physical layer devices. The system includes a plurality of low speed physical layer devices and a high speed physical layer device. Each of the physical layer devices is connected to a bus. The bus is coupled to a bus interface device which is coupled to the low speed physical layer devices and the high speed physical layer device. The bus interface device is operable to provide the physical layer devices with equal opportunities to access to the bus. The system also includes an arbiter which is coupled to the low speed physical layer devices, the high speed physical layer device and the bus interface device. The arbiter is operable to provide the high speed device with disproportionately frequent access to the bus.
More specifically, the arbiter is also operable to enable and disable the ability of the physical layer devices to accept an opportunity to access the bus.
In one particular embodiment, the system""s low speed physical layer devices are coupled to DSL modems and the high speed physical layer device is coupled to an OC3 network. A further embodiment can include a system which communicates ATM cells using a UTOPIA 2 protocol. A further embodiment can include a programmable logic device as the arbiter.
In accordance with another aspect of the present invention, a method is provided for managing data communication between physical layer devices. The method comprises using a bus interface device to offer multiple low speed physical layer devices and a high speed physical layer device in-turn access to a bus. An arbiter monitors the offers of in-turn access. The ability of the individual physical layer devices to accept the offers of in-turn access is selectively enabled and disabled such that the high speed physical layer device is ensured disproportionately frequent access to the bus.
A technical advantage of the present invention includes a data communication system that allows for the mixing of a high speed physical layer device with a plurality of low speed physical layer devices such that the high speed device can be a less expensive xe2x80x9coff the shelfxe2x80x9d device with a small first-in first-out (FIFO) buffer.
Another technical advantage of the present invention includes a data communication system and method which protects against data loss. As small office and home office users (SOHO""s) desire increased access to information and, therefore, data carrying capacity, the need for cost effective and reliable systems will increase. The present system and method make possible a less expensive and reliable data communication system which protects against lost data.
A further important technical advantage of the present invention is the polling scheme created within the system. The scheme can prevent the high speed physical layer device from placing useless data on the bus.
Other important technical advantages are readily apparent to one skilled in the art from the following figures, descriptions, and claims.